Transfer case / 4WD Question

[langja]

Looking into a duramax conversion of my 99 C/K 3500 gasser 4x4 truck (old shape).
If installing an 06 / 07 LBZ Allison with corresponding transfer case how does the C/K 4WD front & rear diffs ratios work out?
I understand that the rear end for a diesel needs to be 3.73 to suit the slower revving diesel. How does this suit the transfer to the front axles.
Does the transfer to the front axles occur on a 1:1 ratio or will I have a greater possibility of 'bind up' if the front is for a 4.11 and the rear changed to 3.73?
Cheers
Jon

[DieselDavy]

You have a lot more problems than just the gear ratios with this transplant! But lets just start by answering your basic question. Yes, you will need to get matching gears for your front and rear diffs. just to make this thing driveable. More experienced guys will chime in here I'm sure but I'd say you should be able to start with the ones that are in there. Once you get ALL the other issues worked out, then you could "change gears" if needed.
Good luck with this retrofit. Sounds like a fun project.
(Ask "More Power" about this transplant, he and others have direct experience with this.)

[More Power]

Like DieselDavy said, both differentials need to have the same gearing.

Otherwise, if you have a Duramax, Allison and matching transfer case, everything will fit with minor challenges.

For example, the transfer case driveshaft output uses a 1410 size U-joint. You can have a custom driveshaft built that has a 1410 at the front and a 1350 at the rear - for the rear driveshaft.

[langja]

Thanks for the replies.
Cheers
Jon